Drive shaft shortening for cheap skates

[70bigblockdodge]

I do not have the correct drive shaft for my Charger so thought I would snap a couple of pictures and let you all follow along as I shorten one from inventory. I know that all the nay sayers will cry foul but I have done this many times and it's not your car. I needed to remove 2 7/8th from this one to fit.

First mark a lengthwise line to index it for reassembly, then make a nice straight cut all the way around just behind the weld, careful not to go to deep wall thickness is maybe .090.

You want to keep the insert piece on the yoke section. I add some longitudinal locating lines and measure how far from cut the weight is for later reattachment. I measure the amount it needs to be shortened from the nice straight cut and tape around measuring multiple times as I tape the circumference.

Bad part of a Mopar driveshaft is the rubber mounted inner tube. Using a small air cut off I cut this back a couple of inches. Using some brake clean and a couple different size screw drivers push the rubber back in between the tubes, if you were to shorten it by more than 5-6 inches I would just remove the tube it's only about a foot long.

Then deburr and bevel both pieces for welding, reinsert the yoke section lining up your longitudinal clocking line and tap it down snug. Whichever side I tap last is the one to tack weld first then tap the other side and tack it.

Then finish weld all the way around and add the weight back using the longitudinal reference lines you made earlier.

So there is driveshaft shortening 101 for cheapskates. I can't tell if it is good to 100 mph because the car does not run yet. But I intend to test it fully here shortly. She is coming together, ugly but will be a rolling resto here shortly.

 

[Wollfen]

I have no issues with this method, it's been a popular fix for many years.

 

[300rag]

...
So there is driveshaft shortening 101 for cheapskates....

You posted this in the wrong forum. It should have been in "Later Model C Bodies - The Formal Years". Seriously though, nice job.

 

[moper]

That's how it's done. I've done it a couple times that way. Mine was fine to 120 .

 

[pomonamissel]

yes i say it works , and r/e housings the same way .

 

[Big_John]

Yep, that's the way it's done.

 

[commando1]

Nice tutorial. That was great.
I'll probably never do it but I'll know how if that time comes.

 

[70bigblockdodge]

Nice tutorial. That was great.
I'll probably never do it but I'll know how if that time comes.

Yep I was showing my son how to do this so I snapped some pictures as I went along and thought I would share. Building the exhaust now using pieces out of Jegs catalog (universal Xpipe kit and some flow master B body over the axle pipes) and some mufflers picked up at a swap meet for $20/pair a few years back.

 

[commando1]

Yep I was showing my son how to do this so I snapped some pictures as I went along and thought I would share. Building the exhaust now using pieces out of Jegs catalog (universal Xpipe kit and some flow master B body over the axle pipes) and some mufflers picked up at a swap meet for $20/pair a few years back.

You're a really cheap bastard.
No wonder I like you.

 

[cantflip]

Yep I was showing my son how to do this so I snapped some pictures as I went along and thought I would share. Building the exhaust now using pieces out of Jegs catalog (universal Xpipe kit and some flow master B body over the axle pipes) and some mufflers picked up at a swap meet for $20/pair a few years back.

Excellent...
Been a while since I've seen that... Will this be a street car when finished? If so, you can update us later on using a hose clamp to finish balancing it...

 

[67-Fury]

Dave, Shouldnt that Get Balanced? I saw a Video once where they shortned it themselves and it Snapped the 727 Tailshaft.

 

[70bigblockdodge]

As long as the yokes are timed /indexed properly and the yoke is centered , you did not cut the insert piece off it will ride good. Same as tire balance people get a big head about telling you you need weight on inside, outside, maybe on a front drive wheel but on a zero offset wheel, 3 in 3 out from flange I call BS, a carefully bubble balance will yield same results. The drive shaft has not changed very much at all 2 7/8 less of it, straight cuts and correct index/clocking it is fine.

 

[70bigblockdodge]

yes i say it works , and r/e housings the same way .

I have never done a housing but I do have a 2wd wrecked ram here that I have been debating about narrowing the 9 1/4 with 3.55 and shortening the stock aluminum driveshaft and putting them in the Charger.

Excellent...
Been a while since I've seen that... Will this be a street car when finished? If so, you can update us later on using a hose clamp to finish balancing it...

Yes it will be a road car I have no intention of making it a drag/street&strip car. It has a 4speed manual overdrive, for now 3.23, 27" tall tires it will hopefully loaf along at 70 mph in the low 2k rpm range. With a Thermoquad and headers, free flowing exhaust I'm hoping for high teens maybe 20 mpg on highway. Even if I don't get that I will end up with effortless cruise keeping up with modern interstate traffic.

 

[1978 NYB]

Nice work Dave.

 

[Big_John]

As long as the yokes are timed /indexed properly and the yoke is centered , you did not cut the insert piece off it will ride good. Same as tire balance people get a big head about telling you you need weight on inside, outside, maybe on a front drive wheel but on a zero offset wheel, 3 in 3 out from flange I call BS, a carefully bubble balance will yield same results. The drive shaft has not changed very much at all 2 7/8 less of it, straight cuts and correct index/clocking it is fine.

I think you get into the difference between a static balance and a dynamic (spin) balance.

As I understand it, if the diameter is larger than the length, a static balance will work. If the length is longer (like a driveshaft) than the diameter, then you need to do a dynamic balance.

I've never been a big believer in needing to "spin" balance tires. But... as the tires have gotten wider over the years, nobody does a simple static (bubble) balance anymore.

Chances are good that as long as you index the yokes right (very important!) and put the original balance weight back on, you'll be fine.

 

[65Fury440]

That's impressive, thanks for posting up!
Questions,
What did you use to cut the weld and the tube?
Is there a reason you cut the front of the shaft VS the rear?

I did a Chevy V8 transplant into a Toyota SR5, used the NP 203 T case, and tried to weld up my own shafts, and failed. Vibrated terribly.

 

[70bigblockdodge]

Questions,
What did you use to cut the weld and the tube?
Is there a reason you cut the front of the shaft VS the rear

A air cut off wheel but I have also used a 4 1/2" angle grinder as long as you can keep it from cutting through the insert so it will center in the tube. I cut the weld just ahead of the tube not down the middle of the bead, you need the end to come out cleanly not have it stuck and fight to get it out. I did a GM one because the slip joint was on the front and I was not sure how it was built on that end. I'm sure it would work the same as long as the amount it is shortened fits in the normally smaller diameter and the weight would stay in small diameter. I guess no reason.

 

[70bigblockdodge]

I've never been a big believer in needing to "spin" balance tires. But... as the tires have gotten wider over the years, nobody does a simple static (bubble) balance anymore

Except my cheap ***. Lol
Front driver cars are the only ones I could see the inside outside weights having a difference. I hate weights on a aluminum wheel showing so I put them on the back or use the stick ons in the center. I was okay on the wife's Trailblazer till it shuts off at just over 100, our 300m vibes a little at 85 but I blame that on the cupped used tires on the rear, and my Challenger is good to over 100. I call BS on spin balancing but it is a standard across the board. Best balancer I ever saw was the one at garage of the moving company I worked for, jack the truck up spin the wheel with a electric drum, with a strobe light and a shake measure switch it would flash strobe when tire wobbled down a you looked where tape on tire was brought it to that point and hammer the weight on top. Confusing I know to describe but it worked like a charm. Get it right and retest, the strobe would not even light, the drum speed was about 65-70 mph with tall rubber on the truck.

 

[pomonamissel]

you need axles to bob' that r/e , they kind'a float , retained on the inside the carrier , just stuck a 75 ramcharger 9 1/4 l/s 3.54 in my d100 . my motor don't get that kind of mileage although , but it up from the 3.91's , tires are 285/70-15 14 1/2 to the ground and 29 1/2 tall .

 

[cantflip]

Don't completely disregard balancing... but a drive will prove out if that shaft needs it. The old finish balancers did a good job... the new road force balancers can even make a set of low profiles ride nicer. The key is the if the operator understands what they're doing and gives a crap... two things lacking at your local tire store.

Drive shaft balancing, engine balancing... all have a definite place and need on a car. Close enough will probably work out for most uses... If at the end of the welding the shaft rolled true and the yokes stayed aligned (pics looked good) it should work... if not a balance at a driveline shop should correct it pretty cheap... or a little trial and error with a couple hose clamps...